The invention relates to a high-pass filter comprising a signal line with several capacitors connected in series as well as a ground line, wherein several inductors are connected between the signal line and the ground line.
High-pass filters of this type are used, for example, in telecommunications, in particular, in mobile radio communications. They can be connected, for example, between an antenna and a signal processing device and ensure that signals within a first range of frequencies with a relatively low frequency are attenuated to a considerable extent whereas, on the other hand, signals within a second range of frequencies with a relatively high frequency experience only a minimal attenuation. As a result, the signals of the first range of frequencies can be practically faded out.
High frequency signals are normally transmitted with the aid of coaxial lines which have an inner conductor and an outer conductor surrounding the inner conductor, wherein an insulation layer is arranged between the inner conductor and the outer conductor. In conjunction with the configuration of a low-pass filter, with which signals with a relatively low frequency experience only a very slight attenuation whereas, on the other hand, signals with a high frequency are subject to a very considerable attenuation and are, therefore, practically faded out, it has already been suggested in DE 32 07 422 A1 that additional elements be pushed onto the inner conductor which determine the distance between the inner conductor and the insulation layer, increase the capacitance of the inner conductor and, therefore, form a capacitor between the inner conductor and the outer conductor while, on the other hand, the inner conductor itself form an inductor in the area between two additional elements which increase capacitance. As a result, a low-pass filter can be designed as a coaxial construction in a constructionally simple manner.
The object of the invention is to configure a high-pass filter of the type specified at the outset as a coaxial construction.